Ink printing apparatuses can be used for single or multicolor printing of a printing substrate web, for example a single sheet or a belt shaped recording medium made of the most varied materials (for example paper). The design of such ink printing apparatuses is known, see for example EP 0 788 882 B1. Ink printing apparatuses that operate according to the drop-on-demand (DoD) principle, for example, have a print head or multiple print heads with nozzles comprising ink channels, the activators of which nozzles—controlled by a printer controller—excite ink droplets in the direction of the printing substrate web, which ink droplets are deflected onto said printing substrate web in order to apply printing dots there for a print image. The activators can generate ink droplets thermally (bubble jet) or piezoelectrically.
Given low print utilizations of the ink printing apparatus, not all nozzles of the inkjet print heads are activated in the printing process; many nozzles have downtimes (print pauses), with the consequence that the ink in the ink channel of these nozzles is not moved. Due to the effect of evaporation from the nozzle opening, the danger exists that the viscosity of the ink then varies. This has the consequence that the ink in the ink channel can no longer move optimally and escape from the nozzle. In extreme cases, the ink in the ink channel dries up completely and jams the ink channel, such that a printing with this nozzle is no longer possible.
These problems in particular occur in color printers. For example, here print bars with print heads are arranged in a fixed position relative to one another as a printing unit. For example, print bars with five respective print heads can be provided, respectively one print bar for the colors black, cyan, magenta, yellow. The problem exists that one or more colors are not used, for example in black-and-white printing. Multiple cleaning cycles are then required in order to make the unused print heads accessible again.
Cleaning devices that have cleaning lips (for example rubber lips) for cleaning of inkjet print heads are known. Such a cleaning device is described in US 2008/0106571 A1. The cleaning device provides two cleaning elements made up of a respective cleaning lip and a retaining element for said respective cleaning lip. A housing is provided for each cleaning element. Each cleaning element can be pivoted between two positions. In the first position—the cleaning position for the print heads—the cleaning elements are swung out of their respective housings so that the print heads can be directed over the cleaning lips. In the second position, the cleaning elements have been rotated into their respective housing. In this second position, the cleaning lips can be cleaned. For this, in each housing a nozzle is arranged that sprays a cleaning fluid onto the associated cleaning lip and therefore cleans the cleaning lip of ink residues. Furthermore, in each housing a second nozzle is provided at the level of the cleaning lip and perpendicular to the cleaning lip, which second nozzle sprays air onto the cleaning lip in order to dry it. The cleaning device can subsequently be pivoted into the first position again.
EP 1 310 367 A1 describes cleaning devices with cleaning lips with which the inkjet print heads can be wiped off. The cleaning devices are arranged in associated housings. They are borne on an axle via which the cleaning devices can be rotated out of the housing in order to be able to clean the print heads. If the cleaning devices are moved back into their housing, the cleaning lips are directed along a stripper in order to clean these.